UR3401-MR3X

Internal combustion engine nitro class 21, 3.49 cm³ - ULTIMATE MXR v3 Ceramic TEAM Edition with Airmax filter

This is the .21 Team Edition racing engine from Ultimate MXR v3 Ceramic, featuring 3-channel control and an Ultimate Airmax air filter. This engine is manufactured by the renowned Japanese brand O.S. Engines and is based on their Speed B21 engine with a square bore-to-stroke ratio.

Many manufacturers offer running-in services on test benches with propellers. The problem with this is that whilst this system serves as a running-in process, running-in on the racetrack is still required.

At Ultimate Racing, we wanted to go one step further and offer our customers the opportunity to purchase engines that are fully run-in and ready for competition, without the need for additional running-in - in other words, engines that can be used in the most demanding competitions, just as you receive them, straight out of the box.

To guarantee quality and ensure that all Team Edition engines are run in to exactly the same high standard, we have developed a fully monitored run-in test bench where temperature, RPM and run-in time are monitored at all times. The entire run-in process is carried out with the engine perfectly lubricated to minimise stress and wear on all parts, thereby significantly extending their service life.

During each phase of the run-in, the engine's torque is also monitored, which allows us to determine when the run-in process can be completed. This ensures that all our Team Edition engines are perfectly run in and ready for competition.

Once the running-in is complete, the engines are dismantled, checked part by part and reassembled by our racing team, thereby guaranteeing the highest quality of the product our customers receive.

In addition to the modifications already featured in the previous version - such as the crankshaft, rear crankcase covers, engine block, the innovative 6 and 6.5 mm FlowMax venturi, and the crankcase for increased power without compromising on fuel economy - the V3 features a new, less sensitive main jet to make it easier to find the optimum mixture point.

With this engine, you have an incredible power curve that delivers spectacular power at all times. It delivers linear and smooth power at low revs, making it perfect for rough terrain, whilst also offering high power at medium and high revs and an excellent riding experience. It is one of the engines with the best idle on the market.

Main Features:
Carburetor: Modified OS21J3 carburetor with a redesigned needle holder and high speed needle for more stable performance and more precise tuning.
Crankcase: Same as the v2, where internal fuel flow was improved to achieve extra power and efficiency.
Filter: All Ultimate MXR v3 engines include a complete Ultimate Airmax filter set.
Cooling Head: The Ultimate MXR v3 uses the same cooling head as its predecessor. This 8fin head has a very low center of gravity and is designed to direct most of the airflow directly toward the glow plug. By cooling the plug, we achieve more stable carburetion and idle.
Venturi: The MXR features the new 6.5 mm FlowMax venturi. With an innovative design that is longer than standard O.S. venturis and wider at the base, the new geometry improves fluid dynamics, providing extra power and a noticeable improvement in fuel mileage.
Backplate: The signature red Ultimate backplate is machined from Swiss 7075 T6 aluminum and features two larger channels that improve the engine fuel flow, increasing power and improving consumption.
Sleeve and Piston: Building on the solid foundation of the MXS, the Ultimate MXR features a newly designed engine group with modified ports to adjust intake and exhaust timing, achieving more power without compromising fuel consumption.
Bearings: The Ultimate MXR v3 uses an original O.S. ceramic rear bearing and a front steel double sealed bearing from Ultimate Racing.
Technical Specifications:
Displacement: 3.49 cc
R.P.M. (power): 2.65 PS @ 34,000 rpm
Stroke: Square 16.40 x 16.40 mm
Sleeve: 3 + 1 ports
Rear Bearing: O.S. Ceramic
Front Bearing: Ultimate Racing Steel
Crankshaft: 14 mm balanced with two tungsten inserts
Carburetor: Modified O.S. 21J3 with exclusive needle holder
Glow Plug: P3 Turbo
Weight: 345 g